How customers rate the service they receive from their various internet-connected (or otherwise networked) computing and telephony devices depends to a large extent on the Quality of Experience (QoE) they perceive for internet-delivered (or, more generally, network-delivered) services. The Quality of Experience perceived will depend on the Quality of Service (QoS) that can be achieved end-to-end (e.g. from a consent origin server or a remote device to the user-device in the home). In turn the QoS achieved will depend on a number of network characteristics. Examples of network characteristics include loss, Round Trip Time, jitter and throughput. While QoE is essentially subjective, it can be inferred from a suitably-defined measure of QoS, which can be calculated from network metrics relating to suitably-chosen and measurable network performance characteristics. As will become apparent, a variety of different types of network performance characteristics or combinations thereof may be chosen and/or applicable in defining a measure of QoS. Network operators may be able to measure these in relation to data traversing paths across networks over which they have control, or between devices under their control, but they may not have sufficient control for such measurements over other networks such their customers' “home networks” or “user networks”, or the devices therein.
Wireless access is becoming the predominant means for devices to communicate within home and public networks like WiFi hotspots. The inherent variability in the Quality of Service achieved by the fixed-line network termination equipment and the various wireless devices drives many complaints to network Internet Service Providers (ISPs). The QoS of the final network segment has a significant effect on the Quality of Experience. For ISPs the performance of the home network is a particular problem because it is largely invisible to it and is the ultimate cause of a large number of calls to ISP helplines. There exist various tools for end-users to test the performance of their network. There are also ways for ISPs to monitor performance to the home, such as by using Deep Packet Inspection (DPI) or by placing probes in the home, such as those in accordance with the “SamKnows” scheme, information about which is available online at www.samknows.com. The former (DPI) is computationally intensive and the latter (“SamKnows” probes) only monitor from one specific point within the home network.
Providing a means to monitor network characteristics within the home network can assist in highlighting when a customer problem is due to a home network issue and provide information to end-users to inform them of potential problems, and can also differentiate between problems in a user's home environment (or WiFi hotspot, etc.) and problems in the broadband or access network. This may be applicable in relation to the monitoring of wired as well as wireless (e.g. WiFi-connected) devices.
Some technical areas and concepts of particular relevance to the mechanism to be discussed later will now be summarised:
Quality of Experience (QoE):
A critical driver for home network monitoring solutions is QoE. The correlation between QoE scores and network characteristics has been done by asking test participants to use Internet applications (such as video streaming, web browsing, Voice over Internet Protocol (VoIP), etc.) a number of times, each time with different network characteristics. Participants are asked to rate the QoE on a scale of 1-5, for example. The results from a number of participants are combined to give an average QoE score for different inputs of network characteristics.
Content Caching:
Content (such as website data, or media content such as video content for streamed delivery, for example) may be cached somewhere closer (in network terms) to the end-user. This may be done either as a deliberate policy (“pre-caching”, as is done by Content Delivery Networks (CDNs), for example) or as content is observed as it passes through a network node (“transparent caching”). The purposes of caching generally have been to reduce traffic on the core network and to improve the QoS delivered to end-users (and hence improve QoE), by reducing delay, for example.
WiFi:
One of the major causes of poor QoE in the home is the variability of WiFi in being able to deliver packets from access points to devices in a user's home network. Poor performance from WiFi-connected devices may be caused by a variety of factors, such as devices being too far from a wireless router or access point, the wireless router or access point being turned off or not working properly, the wireless router or access point itself receiving poor service from the external network, interference from other equipment within the home (not necessarily networked devices—equipment such as microwave ovens and cordless phones can cause poor performance from WiFi-connected devices), or authentication issues between networked devices and the wireless router or access point, for example.
Home Gateways/Access Points:
The home gateway performs many of the interfacing functions between the home network and an ISP's network, e.g. allocation of private IP addresses (using the Dynamic Host Configuration Protocol (DHCP)) and translation of public to private address space (Network Address Translation (NAT)). In a large number of cases the role of the home gateway is combined with that of a wireless access point. The home gateway functions could be moved to a location in the ISP's network.
WiFi networks are inherently lossier than wired networks. Packets can become corrupted as they are transmitted on the air interface. There are techniques for correcting small amounts of corruption. Typically these involve providing redundant data in the packets. Where the redundant information is insufficient to recreate the packet data, that packet is effectively lost. Such losses can be corrected by re-transmission between the WiFi device and the access point or home router. This re-transmission is performed at the layer 2 protocol in the OSI stack (i.e. in the data link layer) and is not visible within layer 3 or above (TCP/IP). Packet corruption may be caused, for example, by electro-magnetic interference within the home environment.
Corruption/Loss can affect network characteristics in many ways:                Re-transmission can increase delay (and hence increase Round Trip Time). Higher delay reduces the throughput of TCP which in turn means that the user may be able to perceive a drop in performance. TCP throughput decreases with increased Round Trip Time due to the TCP control algorithm used. The more frequently losses occur, the greater the detrimental effect is likely to be on TCP throughput, and hence on QoE.        Corruption/Loss can increase jitter. Jitter is the variability in Round Trip Time. Increasing jitter can affect some internet applications. One of the severest effects will be on live TV streaming. Jitter will be more severe where a packet has to be re-transmitted several times before it is received.        Corruption/Loss can reduce throughput. As well as the effect of delay potentially reducing TCP throughput, access point behaviour may also have an effect. As well as re-transmitting the lost packets many access points will reduce the sending rate. Essentially the higher the sending rate, the greater the probability of loss. So in a lossy environment throughput is generally reduced to compensate for this.        Loss may not be remediable. This can still happen in WiFi networks where re-transmission has not been successful. Loss can lead to poor QoE. For User Datagram Protocol (UDP) applications, loss will generally involve loss of part of the information being transmitted, e.g. loss of some part of a video frame so that increasing “blockiness” is observed by the user. In TCP applications it can lead to a reduction in throughput due to the way the TCP congestion avoidance algorithm works.        